Not Applicable.
Not Applicable.
The present invention relates generally to a vehicle wheel balancer system or wheel vibration control system configured with an wheel data acquisition arm, and in particular to a wheel data acquisition arm configured with an extended range of motion to accommodate wheel rims of differing inner diameters.
Vehicle wheel assemblies, such as shown at 10 in FIG. 1, consist of a pneumatic tire 12 mounted to a wheel rim 14. The size and configuration of the wheel rim 14 may vary greatly between different vehicle wheel assemblies. These variations may include the number of spokes 16, the setback of the spokes from the inner edge 18 or outer edge 20 of the rim 14, the width of the rim 14, the diameter of the rim 14, and the shape or contour of the rim 14. Currently, the U.S. Department of Transportation has approved, for use on passenger cars and light trucks, a maximum wheel rim diameter of 24 inches, however, wheel rim diameters of 26xe2x80x3 or greater are likely to be approved for use in the United States in the near future.
Conventional vehicle wheel balancing systems or wheel vibration control systems, such as shown at 30 in FIG. 2, include a central processing unit 32, such as a general purpose computer, digital signal processor, or other suitable logic circuit, configured with a software application to identify and correct forces and imbalances in vehicle wheel assemblies 10. The central processing unit 32 receives input from a number of sources, including knobs 34 and keypads 36 for operator input, a memory 38, and one or more imbalance force sensors 40 disposed in operative relationship to a motor driven spindle or shaft 42 upon which a wheel assembly 10 undergoing a balance procedure is mounted.
Imbalance and force measurements, together with other informational output from the central processing unit 32 are displayed to an operator on a video display 44 unit such as a CRT, LCD screen, or LED panel. In addition, the central processing unit 32 is configured to control a motor 46 or other drive unit to regulate the rotational movement and position of the shaft or spindle 42 upon which the wheel assembly 10 is mounted. In some wheel vibration control systems, such as the GSP 9700 Series system, manufactured by Hunter Engineering Co. of Bridgeton, Mo., and shown in FIG. 3, the central processing unit 32 is configured to control a load roller 50 to apply a load to a wheel assembly during rotational movement thereof. The central processor 32 receives feedback from one or more sensors associated with the load roller 50, indicative of radial or lateral forces exerted by the rotating wheel assembly 10.
One function of a vehicle wheel balancer or vibration control system is to identify, to an operator, the location on a wheel rim at which an imbalance correction weight should be applied to correct a detected imbalance in the wheel assembly. Conventionally, as shown in FIG. 4, a at least one multi-function wheel data acquisition arm 60 is utilized to facilitate the weight placement process. The wheel data acquisition arm 60 is disposed parallel to, and adjacent the shaft or spindle 42 upon which the wheel assembly 10 is mounted. A typical wheel data acquisition arm 60 consists of an extending and rotating shaft 62, and a perpendicular rim contact arm 64 affixed to an end of the shaft 62. Alternate designs, such as shown in U.S. Pat. No. 5,447,064 to Drechsler et al., utilize a single telescoping arm secured at a pivot point. A roller or ball 66 is disposed at the end of the rim contact arm 64, and is configured to provide a known contact point between the wheel data acquisition arm 60 and the wheel rim 14. Optionally included at the end of the rim contact arm 64 is an imbalance weight holder or clip, configured to hold an imbalance correction weight to aid in placement on a wheel rim 14.
As seen in FIG. 3, some vehicle wheel balancer or vibration control systems 30 include a second, outer wheel data acquisition arm 61 configured with a roller or ball 63. While the typical wheel data acquisition arm 60 contacts the inner wheel rim 20, or wheel rim surfaces disposed adjacent the balancer or vibration control system 30 when the wheel rim is mounted to the shaft or spindle 42, the second or outer wheel data acquisition arm 61 is disposed to contact the outer wheel rim lip 18. Conventionally, the second or outer wheel data acquisition arm 61 is a fixed length structure capable of rotating through a large arc.
During use, with a wheel installed on the balancer shaft or spindle, the shaft 62 of the wheel data acquisition arm 60 is extended such that the perpendicular rim contact arm 64 is positioned within the center portion of the wheel rim 14. Rotation of the wheel data acquisition arm 60 about the axis of the shaft 62 swings the rim contact arm 64 into contact with an inner surface of the wheel rim 14, at a known angular position for wheel rims of known diameters. Axial movement of the wheel data acquisition arm 60 is tracked by a displacement sensor 68, while rotational movement about the axis is tracked by a rotational sensor 70, with may be either a relative rotational position sensor, or an absolute rotational position sensor. Analog signals from the sensors 68 and 70 are typically converted into digital form via a converter 72, and routed to the central processing unit 32.
When combined with computer controlled rotation of the wheel assembly 10 about the balancer shaft or spindle 42, the movement of the wheel data acquisition arm 60 either delivers an imbalance correction weight carried by a weight holder or clip to a calculated angular position on a wheel rim 14, or provides an operator with a clear visual indication of the weight placement location by contacting the roller or ball 66 at the intended weight placement location.
In addition, by tracking the axial movement of the shaft of the wheel data acquisition arm, and the rotational movement of the rim contact arm about the shaft axis, using sensors 68 and 70, the central processing unit of a conventional wheel balancer system can determine the dimensions, contours, and runout parameters of a wheel rim mounted to the balancer shaft or spindle, as described in U.S. Pat. No. 5,915,274 to Douglas. Determining the dimensions, contours, and runout parameters of the wheel rim permits the central processing unit to identify optimal imbalance correction weight planes, and to present the operator with the best imbalance correction weight arrangement.
Using the determined dimensions, contours, and runout parameters of the wheel rim, the central processing unit 32 of the balancer 30 effectively has an infinite number of imbalance correction planes in which to place imbalance correction weights. The best plane locations, amount of weight, and even the number of weights, are calculated to result in a minimized residual static and dynamic imbalance while still using incrementally sized weights. The display 44 associated with the balancer system 30 is used to show the actual scanned contour of the wheel rim 14, as well as the relative locations of the weights on the displayed wheel rim 14, enhancing operator understanding and providing confidence that the measuring apparatus is working correctly. However, actual placement of the imbalance correction weights in the identified optimal balance correction planes, and at the ideal rotational positions, must still be done manually by an operator, guided by instructions displayed on the wheel balancer, and aided by the wheel data acquisition arm.
The use of a conventional wheel data acquisition arm 60 is, however, limited to wheel rims 14 having an inner diameter in a range between 10.0-22.0 inches, due to mechanical limitations. As seen in FIG. 5, the rim contact arm 64 can rotate about the wheel data acquisition arm shaft 62 between a maximum outward position Pmax, and a minimum inward position Pmin. Rotation of the rim contact arm 64 past the maximum outward position Pmax reduces the distance between the rim contact arm 64 contact point on the wheel rim 14 and the axis of rotation for the wheel rim about the balancer shaft 42. Correspondingly, the minimum inward rotational position Pmin is defined as the point at which the rim contact arm 64 swing is blocked from further rotation by the balancer shaft or spindle 42 upon which the wheel rim 14 is mounted.
Alternative designs for the wheel data acquisition arm 60, such as shown in U.S. Pat. No. 5,447,064 to Drechsler et al. which telescope from a single pivot point, are capable of contact surfaces of wheel rims 14 having greater ranges of diameters, However, due to the mechanical geometry of these designs, they are incapable of determining, with necessary precision, a pivot angle for the telescoping arm sufficient to permit identification of a wheel rim runout.
Accordingly, it will be appreciated that there is a need for a wheel balancer system to include a wheel data acquisition arm which is capable of contacting the inner surfaces of both large and small diameter wheel rims mounted to a balancer shaft or spindle.
Briefly stated, a vehicle wheel balancer system of the present invention incorporates an wheel data acquisition arm configured to transition between at least a first operating position adapted for use with vehicle wheels having a first range of diameters, and at least a second operating position adapted for use with vehicle wheels having a second range of diameters which differ, at least in-part, from the first range of diameters.
In an alternate embodiment, the central processing unit of the vehicle wheel balance system is configured to identify the operating position of the wheel data acquisition arm.
In an alternate embodiment, the wheel data acquisition arm is further configured with an eccentric roller to generate a cyclic signal when the eccentric roller is in contact with the inner surface of a rotating wheel rim during a runout measurement procedure. The central processing unit of the vehicle wheel balancer system is correspondingly configured to utilize the cyclic signal to estimate a diameter of the wheel rim and to identify an operating position of the wheel data acquisition arm.